Apparatus and method using automatic generation of a base dose

ABSTRACT

A control circuit forms a radiation therapy treatment plan by automatically generating a base dose that references dosing information from multiple sources and then using that base dose to optimize a radiation therapy treatment plan. That radiation therapy treatment plan is then used to administer radiation therapy to a patient. That automatically generated base dose can represent any or all of earlier radiation therapy treatments for the patient, a same fraction as a dose presently being optimized per the radiation therapy treatment plan, and future planned fractions for the patient.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of prior U.S. patent application Ser.No. 14/865,703, filed Sep. 25, 2015, now U.S. Pat. No. 10,252,081 B2issued on Apr. 9, 2019, which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

These teachings relate generally to the use of radiation as atherapeutic treatment and more specifically to the formation and use ofcorresponding radiation-treatment plans.

BACKGROUND

The use of radiation to treat medical conditions comprises a known areaof prior art endeavor. For example, radiation therapy comprises animportant component of many treatment plans for reducing or eliminatingunwanted tumors. Unfortunately, applied radiation does not inherentlydiscriminate between unwanted areas and adjacent healthy tissues,organs, or the like that are desired or even critical to continuedsurvival of the patient. As a result, radiation is ordinarily applied ina carefully administered manner to at least attempt to restrict theradiation to a given target volume.

Treatment plans typically serve to specify any number of operatingparameters as pertain to the administration of such treatment withrespect to a given patient using a specific radiation therapy treatmentplatform. Such treatment plans are often optimized prior to use. (Asused herein, “optimization” will be understood to refer to improvingupon a candidate treatment plan without necessarily ensuring that theoptimized result is, in fact, the singular best solution.) Manyoptimization approaches use an automated incremental methodology wherevarious optimization results are calculated and tested in turn using avariety of automatically-modified (i.e., “incremented”) treatment planoptimization parameters.

Treatment plans are typically generated as a function of user-specifieddosimetric goals. In many cases dose optimization proceeds as a functionof both a presently-planned dose (i.e., the dose being optimized for aparticular radiation treatment session) and a so-called base dose. Thebase dose is an aggregated per-patient metric representing the radiationdosage received in earlier radiation treatment sessions (if any), duringthe same day (i.e., “fraction”) (if any) as the session currently beingoptimized, and future sessions as well (if any).

These references to previous and future dosings for a particular patientgenerally refer to dosings that are administered as part of an overallunified and integrated effort to treat a particular unwanted biologicalcondition such as a tumor or group of tumors. Accordingly, and usually,it is not contemplated that the base dose will include radiation dosingsthat might have nothing to do with the present course of treatment suchas, for example, dentistry x-rays. That said, however, in some cases itmay be appropriate to include ancillary exposures of radiation (such asa series of x-rays to view and diagnosis a broken bone or a CT scan todiagnose some other unrelated condition) when computing the base dose.

A typical prior art practice is to manually calculate the base dose bycombining dose distributions from their corresponding different events.Such an approach, of course, is prone to human error, oversight,misinterpretations, and misunderstandings, all of which can lead to aninaccurate base dose. An incorrect base dose, in turn, can lead to asub-optimum radiation treatment plan.

BRIEF DESCRIPTION OF THE DRAWINGS

The above needs are at least partially met through provision of theapparatus and method using automatic generation of a base dose describedin the following detailed description, particularly when studied inconjunction with the drawings, wherein:

FIG. 1 comprises a flow diagram as configured in accordance with variousembodiments of these teachings; and

FIG. 2 comprises a block diagram as configured in accordance withvarious embodiments of these teachings.

Elements in the figures are illustrated for simplicity and clarity andhave not necessarily been drawn to scale. For example, the dimensionsand/or relative positioning of some of the elements in the figures maybe exaggerated relative to other elements to help to improveunderstanding of various embodiments of the present teachings. Also,common but well-understood elements that are useful or necessary in acommercially feasible embodiment are often not depicted in order tofacilitate a less obstructed view of these various embodiments of thepresent teachings. Certain actions and/or steps may be described ordepicted in a particular order of occurrence while those skilled in theart will understand that such specificity with respect to sequence isnot actually required. The terms and expressions used herein have theordinary technical meaning as is accorded to such terms and expressionsby persons skilled in the technical field as set forth above exceptwhere different specific meanings have otherwise been set forth herein.

DETAILED DESCRIPTION

Generally speaking, pursuant to these various embodiments, a controlcircuit forms a radiation therapy treatment plan by automaticallygenerating a base dose that references dosing information from multiplesources and then using that base dose to optimize a radiation therapytreatment plan. That radiation therapy treatment plan is then used toadminister radiation therapy to a patient. That automatically generatedbase dose can represent any or all of earlier radiation therapytreatments for the patient, a same fraction as a dose presently beingoptimized per the radiation therapy treatment plan, and future plannedfractions for the patient.

By one approach the control circuit generates the base dose as afunction of a particular treatment model such that the base dose issuitable for present use in optimizing the radiation therapy treatmentplan. In any event, the control circuit uses this base dose to optimizea radiation therapy treatment plan by, at least in part, using the basedose to limit an accumulation of radiation in a particular volume of thepatient.

These teachings are highly flexible in practice and will accommodatevarious modifications and variations. For example, the aforementionedmultiple sources can include any one or more of treatment records forradiation therapy treatment previously delivered to the patient,radiation therapy treatment plans for undelivered parallel treatment forthe patient, patient images, and patient deformation information, withother sources being possible depending upon the specifics of aparticular application setting.

As another example of the flexibility of these teachings, by oneapproach the control circuit can individually weight the dosinginformation from different sources. Such weighting can reflect, forexample, an actual or perceived relevancy of the source and/or accuracyof the source. In lieu of the foregoing or in combination therewith,when producing a base dose per these teachings the control circuit canalso produce a corresponding indication of uncertainty. That indicationof uncertainty can then be used when optimizing the radiation therapytreatment plan.

So configured, these teachings facilitate efficiently and reliablyaccounting for both delivered and undelivered dosings when optimizing aradiation treatment plan for a particular patient. As one simple examplein these regards, the automatically-calculated base dose can be used inoptimization to limit an aggregate accumulated dose in one or moretarget volumes and untargeted volumes for a particular patient.

These and other benefits may become clearer upon making a thoroughreview and study of the following detailed description. Referring now tothe drawings, and in particular to FIG. 1, an illustrative process 100that is compatible with many of these teachings will now be presented.For the sake of an illustrative example it will be presumed in thisdescription that a control circuit (or plurality of control circuits)carries out the actions, steps, and functions described in this process100. FIG. 2 provides an illustrative example in these regards.

As shown in FIG. 2, a radiation therapy treatment platform 200 caninclude or otherwise operably couple to a control circuit 201. Being a“circuit,” the control circuit 201 therefore comprises structure thatincludes at least one (and typically many) electrically-conductive paths(such as paths comprised of a conductive metal such as copper or silver)that convey electricity in an ordered manner, which path(s) will alsotypically include corresponding electrical components (both passive(such as resistors and capacitors) and active (such as any of a varietyof semiconductor-based devices) as appropriate) to permit the circuit toeffect the control aspect of these teachings.

Such a control circuit 201 can comprise a fixed-purpose hard-wiredhardware platform (including but not limited to an application-specificintegrated circuit (ASIC) (which is an integrated circuit that iscustomized by design for a particular use, rather than intended forgeneral-purpose use), a field-programmable gate array (FPGA), and thelike) or can comprise a partially or wholly-programmable hardwareplatform (including but not limited to microcontrollers,microprocessors, and the like). These architectural options for suchstructures are well known and understood in the art and require nofurther description here.

This control circuit 201 is configured (for example, by usingcorresponding programming as will be well understood by those skilled inthe art) to carry out one or more of the steps, actions, and/orfunctions described herein. It will also be understood that a “controlcircuit” can comprise multiple such components or platforms as suggestedby the phantom control circuit box shown in FIG. 2.

By one optional approach the control circuit 201 operably couples to amemory 202. This memory 202 may be integral to the control circuit 201or can be physically discrete (in whole or in part) from the controlcircuit 201 as desired. This memory 202 can also be local with respectto the control circuit 201 (where, for example, both share a commoncircuit board, chassis, power supply, and/or housing) or can bepartially or wholly remote with respect to the control circuit 201(where, for example, the memory 202 is physically located in anotherfacility, metropolitan area, or even country as compared to the controlcircuit 201).

In addition to radiation treatment plans, dosing information fromvarious sources, and/or base dose information itself, this memory 202can serve, for example, to non-transitorily store the computerinstructions that, when executed by the control circuit 201, cause thecontrol circuit 201 to behave as described herein. (As used herein, thisreference to “non-transitorily” will be understood to refer to anon-ephemeral state for the stored contents (and hence excludes when thestored contents merely constitute signals or waves) rather thanvolatility of the storage media itself and hence includes bothnon-volatile memory (such as read-only memory (ROM) as well as volatilememory (such as an erasable programmable read-only memory (EPROM).)

The radiation therapy treatment platform 200 also includes a therapeuticradiation beam source 203 that operably couples and responds to thecontrol circuit 201. So configured, a corresponding radiation beam 204as emitted by the therapeutic radiation beam source 203 can beselectively switched on and off by the control circuit 201. Theseteachings will also accommodate having the control circuit 201 controlthe relative strength of the radiation beam 204. Radiation sources arewell understood in the art and require no further description here.

In this example the radiation beam 204 is directed towards a multi-leafcollimator 205 that also operably couples to the control circuit 201 tothereby permit the control circuit 201 to control movement of thecollimator's leaves and hence the formation and distribution of one ormore radiation-modulating apertures. Multi-leaf collimators arecomprised of a plurality of individual parts (known as “leaves”) thatare formed of a high atomic numbered material (such as tungsten) thatcan move independently in and out of the path of the radiation-therapybeam in order to selectively block (and hence shape) the beam. Typicallythe leaves of a multi-leaf collimator are organized in pairs that arealigned collinearly with respect to one another and that can selectivelymove towards and away from one another via controlled motors.

By passing radiation beam 204 through the aperture(s) of a multi-leafcollimator 205 the radiation beam 204 can be modulated to provide amodulated radiation beam 206 that better matches the dosing requirementsof the treatment session. These dosing requirements typically include(or at least presume) prescribing which body tissues to irradiate andwhich body tissues to avoid irradiating. The resultant modulatedradiation beam 206 then reaches a treatment target in a correspondingpatient 207.

In this illustrative example the control circuit 201 may optionally alsooperably couple to one or more information sources 208. As will bediscussed further below, these information sources 208 may containdosing information pertaining to the patient 207. That dosinginformation can comprise, but is not limited to, past, present, and/orfuture radiation-exposure events for the patient 207. The informationsources 208 themselves may comprise a variety of information-harboringplatforms (including but not limited to computers, memories, databases,servers, and the like) or can even comprise the aforementioned controlcircuit 201 and/or memory 202 themselves.

With continuing reference to both FIGS. 1 and 2, this process 100begins, at block 101, with using the control circuit 201 to form aradiation therapy treatment plan. This activity includes automaticallygenerating a base dose that references dosing information from multiplesources. By one approach, if desired, this activity can comprisegenerating the base dose as a function of a particular treatment modelsuch that the base dose is suitable (i.e., compatible or normalized) forpresent use in optimizing this particular radiation therapy treatmentplan. For example, biological modeling can serve to estimate a singledose distribution having a same biological effect as a combined effectof the multiple sources.

Regardless of how ultimately represented, the generated base dose willtypically serve to represent at least two of one or more earlierradiation therapy treatments for this patient 207, a same fraction as adose presently being optimized per the radiation therapy treatment plan,and future planned fractions for the patient 207 per the present overallradiation treatment regimen. In a typical application setting all ofthese dosing events constitute an integral part of the same overallradiation treatment regimen. That said, if desired, other dosing eventscan be included if desired, including, for example, dosing owing toimaging events and the like.

As noted above, the foregoing dosing information is accessed from(directly or directly) a plurality of sources. These teachings willaccommodate receiving such information from a variety of differentsources of the same type. These teachings will also accommodate avariety of different types of sources including, but not limited to,treatment records for radiation therapy treatment previously deliveredto the patient 207 (including but not limited to radiation therapytreatment plans for previously-delivered dosings), radiation therapytreatment plans for undelivered parallel treatment for the patient 207,and patient images (where, for example, the control circuit canascertain from the image, either directly or indirectly, which volumesof the patient 207 were exposed to imaging radiation and from whatrelative angle(s)).

These teachings will also accommodate using patient deformationinformation as a source. When treatment planning (including planoptimization) is being performed, it is usual that a relatively recentpatient image is used as basis for the treatment plan generation. If thepatient 207 has received a previous dose or has a future planned dosethat is defined in an earlier/other patient image (with differentpatient geometry), the dose distribution(s) suitable for being used as abase dose can to be brought to the new patient image (which is used forthe plan optimization). A deformable registration can be a vector fieldthat describes how two geometries are related. The vector field can beused, for example, for sampling dose levels from the first geometry tothe second geometry. Therefore, when a deformable registration isavailable, it is possible to optimize a treatment dose for a cell in a(new) patient image which (cell) is known to have accumulated a certaindose level in another (earlier/other) patient geometry.

Generally speaking, once all of the dosing information has beenretrieved from these various sources, that dosing information can besummed to generate the base dose. If desired, the control circuit 201can be further configured to assess and compare these various discretedosing events and/or sources to identify possibly redundant content. Ifand when redundant or otherwise overlapping dosing information exists,the control circuit can, for example, delete redundant information toavoid overestimating the base dosage. By one approach, when informationis available to assess precision and/or accuracy, the control circuit201 can delete redundant information that is characterized as being theleast reliable. By another approach, the control circuit 201 can beconfigured to calculate an average for any instances of redundantinformation and utilize that resultant average as the representativedosing value.

The control circuit 201 then utilizes that automatically calculated basedose to optimize a radiation therapy treatment plan. For example, thecontrol circuit 201 can use the calculated base dose to limit anaccumulation of radiation in one or more volumes of the patient 207including both treatment targets and untargeted areas where radiation ispreferably avoided.

By one approach, where, for example, the control circuit 201 hasinformation regarding relevancy of a particular source of doseinformation and/or accuracy of a particular source of dose information,the control circuit 201 can individually weight the dosing informationfrom various sources to reflect that sense of relevancy and/or accuracy.That weighting can then serve to provide a basis for also developing acorresponding indication of uncertainty regarding the generated basedose. When available, that indication of uncertainty can be utilizedwhen optimizing the radiation therapy treatment plan. For example, theoptimization parameters may be set to favor observing the highestpossible base dose but to permit using lower base doses if necessary toachieve one or more other treatment plan objectives.

So configured, these teachings can facilitate not only automaticallycalculating a base dose that can be reliably and effectively used whenoptimizing a corresponding radiation treatment plan, but can helpresolve uncertainties that can arise when facing conflicting metricsthat purport to represent a same dosing event and or that can helpaccommodate uncertainties regarding the accuracy of the original data.Overall, these teachings can reduce the time required to calculate ausable base dose while simultaneously helping to ensure the accuracy ofthe calculated result and hence the integrity of the resultant optimizedradiation treatment plan.

At block 102 that radiation therapy treatment plan can then be used toadminister radiation therapy to a patient 207.

Those skilled in the art will recognize that a wide variety ofmodifications, alterations, and combinations can be made with respect tothe above described embodiments without departing from the scope of theinvention, and that such modifications, alterations, and combinationsare to be viewed as being within the ambit of the inventive concept.

What is claimed is:
 1. A method comprising: forming a radiation therapytreatment plan using a control circuit by: automatically generating abase dose that references dosing information from multiple sources by,at least in part, individually weighting the dosing information from themultiple sources; and using the base dose to optimize a radiationtherapy treatment plan; and using the radiation therapy treatment planto administer a radiation therapy treatment to a patient.
 2. The methodof claim 1, wherein the base dose represents at least two of: earlierradiation therapy treatments for the patient; a same fraction as a dosepresently being optimized per the radiation therapy treatment plan; andfuture planned fractions for the patient.
 3. The method of claim 1,wherein automatically generating a base dose that references dosinginformation from multiple sources comprises, at least in part,generating the base dose as a function of a particular treatment modelsuch that the base dose is suitable for present use in optimizing theradiation therapy treatment plan.
 4. The method of claim 1, whereinusing the base dose to optimize a radiation therapy treatment plancomprises, at least in part, using the base dose to limit anaccumulation of radiation in a particular volume of the patient.
 5. Themethod of claim 1, wherein the multiple sources include at least one of:treatment records for a radiation therapy treatment previously deliveredto the patient; radiation therapy treatment plans for an undeliveredparallel radiation therapy treatment for the patient; patient images;and patient deformation information.
 6. The method of claim 1, whereinindividually weighting the dosing information from the multiple sourcescomprises individually weighting the dosing information as a function,at least in part, of at least one of: relevancy of a source of themultiple sources; and accuracy of a source of the multiple sources. 7.The method of claim 1, wherein automatically generating a base dose thatreferences dosing information from multiple sources comprises, at leastin part, producing a base dose and a corresponding indication ofuncertainty.
 8. The method of claim 1, wherein automatically generatinga base dose that references dosing information from multiple sourcescomprises using biological modeling to estimate a single dosedistribution having a same biological effect as a combined effect of themultiple sources.
 9. An apparatus comprising: a control circuitconfigured to form a radiation therapy treatment plan by: automaticallygenerating a base dose that references dosing information from multiplesources by, at least in part, individually weighting the dosinginformation from the multiple sources; and using the base dose tooptimize a radiation therapy treatment plan; and a radiation therapytreatment platform configured to use the radiation therapy treatmentplan to administer a radiation therapy treatment to a patient.
 10. Theapparatus of claim 9, wherein the base dose represents at least two of:earlier radiation therapy treatments for the patient; a same fraction asa dose presently being optimized per the radiation therapy treatmentplan; and future planned fractions for the patient.
 11. The apparatus ofclaim 9, wherein the control circuit is configured to automaticallygenerate the base dose that references dosing information from multiplesources by, at least in part, generating the base dose as a function ofa particular treatment model such that the base dose is suitable forpresent use in optimizing the radiation therapy treatment plan.
 12. Theapparatus of claim 9, wherein the control circuit is configured to usethe base dose to optimize a radiation therapy treatment plan by, atleast in part, using the base dose to limit an accumulation of radiationin a particular volume of the patient.
 13. The apparatus of claim 9,wherein the multiple sources include at least one of: treatment recordsfor a radiation therapy treatment previously delivered to the patient;radiation therapy treatment plans for an undelivered parallel radiationtherapy treatment for the patient; patient images; and patientdeformation information.
 14. The apparatus of claim 9, wherein thecontrol circuit is configured to individually weight the dosinginformation from the multiple sources by individually weighting thedosing information as a function, at least in part, of at least one of:relevancy of a source of the multiple sources; and accuracy of a sourceof the multiple sources.
 15. The apparatus of claim 9, wherein thecontrol circuit is configured to automatically generate a base dose thatreferences dosing information from multiple sources by, at least inpart, producing a base dose and a corresponding indication ofuncertainty.
 16. The apparatus of claim 9, wherein the control circuitis configured to automatically generate a base dose that referencesdosing information from multiple sources by using biological modeling toestimate a single dose distribution having a same biological effect as acombined effect of the multiple sources.